Question

A company that manufactures bookcases finds that the average time it takes an employee to build a bookcase is 20 hours with a standard deviation of 5 hours. A random sample of 49 employees is taken. What is the likelihood that the sample mean will be 23 hours or more? Please use the right z table.

Answer 1

Solution :

Given that,

mean = = 20

standard deviation = = 5

n = 49

= 20

  =  ( /n) = ( 5 / 49 ) =0.7143

P ( x > 23 )

= 1 - P (x < 23 )

= 1 - P ( x -  / ) < ( 23 - 20 / 0.7143)

= 1 - P ( z < 3 / 0.7143 )

= 1 - P ( z < 4.20)

Using z table

= 1 - 1

= 0

Probability = 0